The ionization constant of heavy water (D2O) in the temperature range 298 to 523 K

1976 ◽  
Vol 54 (22) ◽  
pp. 3553-3558 ◽  
Author(s):  
David William Shoesmith ◽  
Woon Lee

The ionization constant of liquid D2O has been measured over the temperature range 298 to 523 K using an aqueous electrolyte concentration cell. Values for the standard free energy, enthalpy, entropy, and heat capacity of ionization have been calculated. The results are compared to similar results for liquid H2O

1969 ◽  
Vol 47 (22) ◽  
pp. 4199-4206 ◽  
Author(s):  
R. E. Robertson ◽  
B. Rossall ◽  
S. E. Sugamori ◽  
L. Treindl

Rates of solvolysis of methanesulfonyl chloride and benzenesulfonyl chloride have been determined in H2O and D2O. The free energy, enthalpy, entropy, and heat capacity of activation were calculated. The exceptional accuracy of the data permitted an estimation of dΔCp≠/dT from a four parameter temperature dependence of the kinetic rates.From these data we conclude that both sulfonyl chlorides hydrolyse by the same mechanism (Sn2) The change in R from CH3 to C6H5 in RSO2Cl did not alter ΔCp≠ but ΔS≠ (20°) was changed from −8.32 to −13.25 cal deg−1 mole−1, respectively. The significance of this difference is attributed to the probability of bond formation rather than to differences in solvent reorganization.


1971 ◽  
Vol 25 ◽  
pp. 361-363 ◽  
Author(s):  
Pentti Salomaa ◽  
Marja Mattsén ◽  
Hans Sievertsson ◽  
Inger Skånberg ◽  
Karl-Gustav Svensson ◽  
...  

1973 ◽  
Vol 51 (15) ◽  
pp. 2590-2595 ◽  
Author(s):  
Digby D. MacDonald ◽  
P. Butler ◽  
D. Owen

High temperature aqueous electrolyte concentration cells with and without liquid junction are described. These cells were used to measure the ionization constant of water in 0.1, 0.25,0.5, and]1.0 mol/kg KCl solutions at temperatures to 200 °C. Extrapolation to infinite dilution yielded the following functions for the temperature dependence of log Kw0 and the thermodynamic parameters for ionization: log Kw0 = −4046.16/T + 3.537 − 0.01323T; ΔG0 = 77458.0 − 67.71T + 0.253187T2 J/mol; ΔH0 = 77458.0 − 0.253187T2 J/mol; ΔS0 = 67.71 − 0.5063T J/K mol; ΔCp0 = −0.5063T J/K mol.


1974 ◽  
Vol 27 (9) ◽  
pp. 1905 ◽  
Author(s):  
DJT Hill ◽  
LR White

The solubility of hexan-1-ol and heptan-1-ol in water has been measured over the temperature range 278-308 K. The free energy, enthalpy and heat capacity of solution of these alcohols has been calculated from this data and the enthalpy and heat capacity have also been obtained by direct calorimetric measurement. The thermodynamic function changes on solution of these two alcohols follow the pattern of the lower members of the homologous series. The results have been compared qualitatively with data for the other alcohols and for the hydrocarbons.


2020 ◽  
Author(s):  
Nayyereh hatefi ◽  
William Smith

<div>Ideal{gas thermochemical properties (enthalpy, entropy, Gibbs energy, and heat capacity, Cp) of 49 alkanolamines potentially suitable for CO2 capture applications and their carbamate and protonated forms were calculated using two high{order electronic structure methods, G4 and G3B3 (or G3//B3LYP). We also calculate for comparison results from the commonly used B3LYP/aug-cc-pVTZ method. This data is useful for the construction of molecular{based thermodynamic models of CO2 capture processes involving these species. The Cp data for each species over the temperature range 200 K{1500 K is presented as functions of temperature in the form of NASA seven-term polynomial expressions, permitting the set of thermochemical properties to be calculated over this temperature range. The accuracy of the G3B3 and G4 results is estimated to be 1 kcal/mol and the B3LYP/aug-cc-pVTZ results are of nferior quality..</div>


Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 471
Author(s):  
Constantino Grau Turuelo ◽  
Sebastian Pinnau ◽  
Cornelia Breitkopf

Modeling of thermodynamic properties, like heat capacities for stoichiometric solids, includes the treatment of different sources of data which may be inconsistent and diverse. In this work, an approach based on the covariance matrix adaptation evolution strategy (CMA-ES) is proposed and described as an alternative method for data treatment and fitting with the support of data source dependent weight factors and physical constraints. This is applied to a Gibb’s Free Energy stoichiometric model for different magnesium sulfate hydrates by means of the NASA9 polynomial. Its behavior is proved by: (i) The comparison of the model to other standard methods for different heat capacity data, yielding a more plausible curve at high temperature ranges; (ii) the comparison of the fitted heat capacity values of MgSO4·7H2O against DSC measurements, resulting in a mean relative error of a 0.7% and a normalized root mean square deviation of 1.1%; and (iii) comparing the Van’t Hoff and proposed Stoichiometric model vapor-solid equilibrium curves to different literature data for MgSO4·7H2O, MgSO4·6H2O, and MgSO4·1H2O, resulting in similar equilibrium values, especially for MgSO4·7H2O and MgSO4·6H2O. The results show good agreement with the employed data and confirm this method as a viable alternative for fitting complex physically constrained data sets, while being a potential approach for automatic data fitting of substance data.


Holzforschung ◽  
2002 ◽  
Vol 56 (1) ◽  
pp. 91-97
Author(s):  
Kei Morisato ◽  
Yutaka Ishimaru ◽  
Hiroyuki Urakami

Summary To understand the swelling phenomenon of wood in liquids,the saturated amount of adsorption of liquids onto wood and the standard free energy changes of the adsorption were determined. The saturated amount of adsorption obtained by regression for several liquids decreased with increasing molecular size of the solvents. The mechanism of wood swelling is discussed systematically taking all the liquids examined in previous experiments into account. Since methanol molecules require more energy for release from cohesive interactions within bulk liquids in the adsorption onto pre-swollen wood,the values of free energy change of adsorption for methanol were lower than the values for acetone,although the relative swelling with methanol was higher. These results suggest that although the cohesive interaction within the bulk liquids reduces adsorptivity,the phenomenon of wood swelling is influenced not only by monolayer adsorption but also by multilayer adsorption. Therefore,the cohesive interaction within the bulk liquids reduces adsorptivity but enhances the condensation which strongly influences the swelling of wood.


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